“It’s something that would completely spoil the beauty of our natural environment and all the things that we do.”

The home lies inside the boundary of the South Downs National Park. Its owners had presented two options for the extension – featuring a pitched or flat roof.

Council officers had argued the former would have been unacceptably ‘unneighbourly’ but felt the latter would ‘hardly be visible’.

But Mrs Dickenson’s daughter, Marnie Williams, was on the verge of tears as she spoke in objection to the plans.

She said: “She enjoys the life, the birds, the pheasants that come into the garden and from all the pictures that you have seen, what you haven’t seen is in that field there are horses. All of these things are going to be stopped by that building.”

Salvington ward councillor Michael Cloake told the committee the plans represented ‘creeping’ development in the national park, which would create an unacceptable outlook for the Dickensons.

“I worry about the creeping development that could quite easily come into applications like this in the future, especially when we have got such a pressure of housing in Worthing,” he said.

Objectors were supported by Noel Atkins, also a Salvington councillor. The rest of the committee approved the application. Chairman Kevin Jenkins said: “We have to preserve the South Downs National Park but it can’t be preserved in its shape or form for an entirety.

“I find it hard to understand how a dark, single-storey building would impact on the enjoyment of a view.”

Councillor Edward Crouch said it was impossible not to be moved by the objectors’ comments but noted planning rules required them to balance the views of many against private interest.